1. Field of the Invention
The present invention relates generally to the field of manufacturing plastic pipes, and more particularly, is directed to an attachment to a pipe belling machine to load resilient gaskets successively and automatically onto a belling mandrel during each cyclical operation of the mandrel in order to produce a belled pipe end complete with the gasket encapsulated within the bell construction.
2. Discussion of the Prior Art
Plastic pipes for various commercial and industrial applications have long been in use and a great majority of such plastic pipes are fabricated of heat softenable material, for example, polyethylene plastic of suitable diameter and thickness for the intended use. Industry recommendations and government specifications have been developed throughout the years to standardize manufacturing objectives and product production whereby known pipe dimensional and quality parameters have now been placed in use on an industry-wide basis.
Plastic pipes are normally used in both pressure and atmospheric piping systems. Considerable energies have been expended by prior workers in the art to develop pipe joining systems which can be readily field constructed and which at the same time can be predictably and reliably considered to be trouble-free and leak-proof after installation. In the most common types of plastic pipe piping systems, the pipes comprising the pipe line will be furnished in usual ten foot lengths or twenty foot lengths. The piping system can be made up by securing the pipe lengths together by employing a sufficient number of pipe lengths to span the entire designed length of the main pipe line and any branches that may be connected thereto. In order to join the individual lengths of pipe in end-to-end juxtaposition, it is now the common practice to treat one end of each length of pipe in a manner to expand or bell that end to form an enlarged socket or bell shape to receive therein the unbelled end of the next adjacent length of plastic pipe. In order to fabricate the expanded or belled end, automatic pipe belling machines are now in common use whereby one end of each length of plastic pipe can be automatically heated to thereby soften that end as the pipe length itself is transversely indexed across the machine to a pipe belling station. A reciprocating mandrel is usually situated at the belling station whereby the previously softened end of the pipe can be shaped to a predetermined profile by the belling mandrel. Upon cooling the pipe end and removing the mandrel, a permanently shaped bell or socket will then be provided in each length of plastic pipe. Typical of such mechanisms is the pipe belling machine disclosed and described in U.S. Pat. No. 4,574,942 wherein the present applicant was the inventor of the said machine.
More recently, in order to facilitate the insertion of a resilient gasket into the belled end of the pipe to provide leak-proof junctions upon joining adjacent lengths of pipe, improved mandrels have been developed whereby a radially reciprocating component can be designed to alternately expand and retract from the peripheral surface of the mandrel during the belling process to automatically impress a radially inwardly open, circular groove in the pipe bell to receive and secure a sealing gasket therewithin prior to use. One such belling mandrel has been disclosed and described in U.S. Pat. No. 4,545,951, which patent is also owned by the present applicant. While the automatic pipe belling machines which are known in the prior art and the belling mandrels with or without expanding segments are also known in the prior art, experience has shown that the proper insertion of the resilient, sealing gasket within the belled pipe end remains a time consuming and tedious job which can add significantly to the total cost of the finished product and to the reliability of the piping system after it has been made up in the field.
Accordingly, the need remains to provide an improved apparatus and method for inserting a resilient gasket within the belled end of a length of plastic pipe.